Effects of wildfire smoke

As if the heat weren’t enough, certain areas of the state have been socked in with smoke from the many wildfires burning not only in our state, but all over the west again. This poses a challenge for wine grape growers in the form of smoke taint, but what about apples? The biggest issue with smoke in apples is that by filtering direct sunlight, it can create the illusion that it is actually providing protection against sunburn, and additional tactics can be relaxed. We’ve learned the hard way that this isn’t the case, and cooling methods should still be used.

While the sunlight may be filtered, the heat can still cause issues and cooling is still warranted based on temperatures. We saw this in 2017 when North Central Washington was blanketed with thick wildfire smoke for several consecutive weeks in the summer and fall:


Another concern with wildfire smoke is its potential effect on fruit maturity. Wood smoke contains about 2000 ppm ethylene, which can advance apple maturity if exposure is constant for a prolonged period of time. Fortunately, the response doesn’t seem to be as dramatic as an application of ethephon would be, but if exposure is constant for several weeks, it does seem to have a subtle effect on accelerating maturity by about 5 – 7 days based on what we saw in 2017. I don’t think we’ve had exposure long enough anywhere in Washington this season for that to happen except perhaps in northern Okanogan County.

Byron Phillips, Wilbur-Ellis Key Account Manager